In crop production, there is a continuous need for agricultural compositions and treatments that improve the health of plants. Healthier plants are desirable since they result in better yields and/or a better quality of the plants or crops. Healthier plants also better resist biotic and/or abiotic stress. A high resistance against biotic stresses in turn allows a lower quantity of applied pesticides, which can then slow down the development of resistances against the respective pesticides.
Hypersensitive response (“HR”) elicitor proteins (also known as harpin proteins) elicit disease resistance in plants and increase plant growth. U.S. Pat. No. 6,277,814 describes a method of enhancing growth in plants, which involves applying an HR elicitor polypeptide or protein in a non-infectious form to plants or plant seeds under conditions to impart enhanced growth to the plants or to plants grown from the plant seeds. These methods are carried out to affect any form of plant growth enhancement or promotion, including greater yield, increased quantity of seeds produced, increased percentage of seeds germinated, increased plant size, greater biomass, more and bigger fruit, earlier fruit coloration, and earlier fruit and plant maturation. Early germination and early maturation permit crops to be grown in areas where short growing seasons would otherwise preclude their growth in that locale. Increased percentage of seed germination results in improved crop stands and more efficient seed use. Greater yield, increased size, and enhanced biomass production allow greater revenue generation from a given plot of land.
Agricultural compositions containing isolated HR elicitor proteins have been used to improve plant health and increase yield. For example, PCT Publication No. WO 04/057957 to Wei teaches increasing the efficacy of an agricultural chemical by applying at least one agricultural chemical and at least one HR elicitor protein or polypeptide to a plant or plant seed under conditions effective to increase the efficacy of the agricultural chemical.
There is a need for agricultural compositions and plant treatments that offer a synergistic effect on plant yield, meaning the combined effects of the agents is greater than the additive effects of each individual agent.
The present invention is directed to overcoming these limitations in the art.